Dental chair base



FIG. 1 is a right side perspective view of a dental chair base showing my new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a front view thereof.

The broken lines shown herein are for illustrative purposes only and form no part of the claimed design. The rear and bottom of the portion of the dental chair base form no part of the claimed design. 

The ornamental design for a dental chair base, as shown and described. 